As is known in the art, a map is a visual representation of a geographic. A map may include symbolic depictions highlighting relationships between elements of a space or a defined geographic region such as objects, regions within the defined geographic region, and themes. Some maps are static two-dimensional, geometrically accurate representations of a three-dimensional space, while others are dynamic or interactive, even three-dimensional. Although most commonly used to depict geographic regions, maps may also represent any space, real or imagined, without regard to context or scale.
As is also known, map imagery data (i.e. data which represents a map image) can be stored as a digital image. A digital image is an image which may be represented as a two-dimensional array of pixels with each of the pixels represented by a digital word. A digital image can be stored in electronic devices which utilize computer programs (also referred to as applications) to render the map imagery data on a display for viewing by a user (e.g. via a display screen on the electronic device).
As is also known, map imagery data may be stored in one or more databases. There are a variety of types of map databases. One particular type of map database is a compressed arc digitized raster graphic (CADRG) database. A CADRG database includes map data that is separated into discreet groupings, each representing a particular geographic or map scale. A map data viewer system provides a means and method of displaying map data from such a database. Typically, the user of such an application must provide three inputs as follows: (1) a location (2) a map scale; and (3) and a selection of the map data to display. Depending upon how these inputs are presented in a graphical user interface (GUI), they can present significant complexity to the user.
As is further known, many map data viewer systems provide a combination box/toggling mechanism which allows a user to switch between different map scales. Other systems render all the scales overlaid into one view. Finally, systems such as Google™ Earth, which are able to directly control a map data set, provide satellite imagery (i.e., imagery of the Earth's surface) taken at different discreet scales to emphasize different surface features.
U.S. Pat. No. 7,379,063, assigned to the assignee of the present application, describes a system and technique for scaling, rotating, and translating map data on a low power platform. The system and technique described therein explains a way to place different “maps” (bitmaps) into a single “world space” coordinate system. The process can be compared to taking multiple satellite images of an area, concatenating them together into a single satellite image, which can then be zoomed/rotated/translated.